Gaseous fuel burner



I Jan. 11, 1938. o. A CAMPBELL 2,105,344

flake/22(7):

Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE GASEOUS FUEL BURNER Donald A. Campbell, Rockford, 111., assignor to Garnet W. McKee, Rockford, Ill.

The present invention relates generally to gas eous fuel burners for furnaces and like heating Y apparatus. More particularly the invention relates to that type of burner which is designed primarily to burn a combustible mixture f air and a gas such as butane or natural gas and consists of a tube-like member which is adapted to have the fuel mixture supplied to one end thereof under pressure, embodies at its other end means 1 for connection to a tuyre in one wall of the furnace with which the burner is used, and has a longitudinal fuel passage therethrough with a short inwardly tapered mouth, a comparatively long narrow throat, and an outwardly flared out- 15 let of intermediate length. I

One object of the invention is to provide a gaseous fuel burner of this type which embodies a novel and comparatively simple device whereby the fuel mixture passing through the passage in 2 the tube-like member may readily be ignited in connection with starting of the burner.

Another object of the invention is to provide a fuel burner of the last mentioned character in which the device for igniting thefuel mixture 25 passing through the longitudinal passage in the tube-like member is located outside of the inlet 35 a gaseous fuel burner of the type and character under consideration in which the igniting means for the fuel mixture comprises an expansion chamber which communicates with, and extends laterally from, the throat portion of the-fuel pas- 40 sage in the tube-like member and is connected by a tube along the outside of the member to receive a small portion of the mixture from the mouth portion of the passage, and also comprises a spark plug of standard or conventional design for ig- 45 niting the portion of the fuel mixture in the expansion chamber in order to produce a flame which traverses the throat portion of the fuel passage and ignites the fuel mixture passing therethrough to the outwardly flared outlet.

m) A further object of the invention is to provide a gaseous fuel burner of the last mentioned character in which the expansion chamber which constitutes a part of the igniting device for the fuel mixture passing through the tube-like member 5:, ,is formed in an open ended plugyhich carrie the spark plug and extends into a hole in the tube-like member.

A still further object of the invention is to provide a gaseous fuel burner of the type and character last mentioned in which the plug formed expansion chamber of the fuel igniting device is so arranged and formed that upon stoppage of the supply of current to the spark plug at the conclusion of a burner igniting operation the flame which is generated in the chamber as the result of the passage of a portion of the fuel mixture therethrough is automatically extinuished and hence there is no likelihood of fouling the spark plug.

Other objects of the invention and the various advantages and characteristics of the present gaseous fuel burner will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by claims at the conclusion hereof.

In the drawing which accompanies and forms a part of this specification or disclosure and in which like numerals of reference denote correspending parts throughout the several views:

Figure l is a vertical longitudinal section of a gaseous fuel burner with a fuel igniting device embodying the invention; and

Figures 2 and 3 are vertical transverse sectional views on the lines 2-2 and 3--3 of Figure 1, respectively.

The burner which is shown in the drawing constitutes the preferred embodiment of the invention and is characterized by the fact that it 3 includes a simple and novel fuel igniting device. It is designed primarily to burn a combustible mixture of air and a gas such as butane or natural gas, comprises a tube-like member 4, and is adapted primarily for use in connection with a furnace F having a tuyere I. The furnace F embodies a side wall 1 having a hole I therein through which the tuyere T extends. The tuyre, as shown in the drawing, projects outwardly a small. distance beyond the side wall 1 of the furnace and embodies on the outer end thereof ,tuyere and. embodies a circular opening f in alignment with the cylindrical entrance t of the v tuyere.

The tube-like member 4 of the burner is axially aligned with the tuyere T. It is formed of steel or any other suitable material and is adapted to receive the fuel mixture under pressure by way of a pipe 5 which surrounds the outer or inlet end of the member 4 and is held in place by means of a screw thread connection 6. The inner or discharge end of the tube-like member 4 is in the form of a reduced or stem-like extension I which extends through the hole f in the plate f and fits within the cylindrical entrance t of the tuyere T. A ring type plate 8 serves to secure the burner in place as far as the tuyere T is concerned. This plate is connected by a screw thread 9 to the inner end of the stem-like extension and is clamped against the hole defining portion of the plate f by means of a pair of bolts Ill. The latter, as shown in Figure 1, extend through holes III in the outer margin of the plate 8 and fit within internally threaded sockets in the plate f of the furnace F. The inner periphery of the tube-like member 4 defines a longitudinal passage II through which the fuel mixture passes from the discharge end of the pipe 5 to the entrance t of the tuyre T. This passage embodies a short mouth I2, a narrow throat I3 and an outwardly flared outlet I4. The mouth I2 is located at the inlet end of the tube-like member 4 and is inwardly tapered. The throat I3 extends from the mouth I2 to the stem-like extension I at the discharge end of the member 4 and there joins and communicates with the outlet I4. It is circular in cross-section and is of uniform diameter from one end thereof to the other. The outlet I4 is located in the stem-like extension I and discharges into the cylindrical entrance t of the tuyere T. The fuel mixture in traveling through the passage II first enters the mouth I2, then flows through the throat I3 and finally passes through the outwardly flared outlet I4 into the entrance of the tuyere. Due to the inward taper of the mouth I2 the velocity of the fuel mixture is materially increased as the mixture passes into the throat I3. This increased velocity of the mixture is maintained during flow of the mixture through the throat due to the fact that the throat is narrower than the mouth and is of uniform diameter from one end thereof to the other. When the fuel mixture passes into the outlet I4 of the throat I3 the velocity of the mixture decreases due to the outward flare of the outlet. Upon entry of the fuel mixture into the tunnel t combustion takes place. During normal operation of the burner no combustion of the gas takes place in the throat I3. This is due to the fact that the velocity at which the mixture passes through the throat is above, that is, in excess of, the rate of flame propagation of the gas. The fuel mixture as it enters the mouth I2 of the passage II is under static pressure and as it flows through the throat I3 is under velocity pressure. When the fuel mixture passes through the outlet I4 it is again under static pressure due to the outward flare of said outlet.

The igniting device for the burner is disposed for the most part on the outside of the tubelike member 4 and consists of an elongated plug I5, a tube I6 and a spark plug I1. The plug I5 is disposed in an upstanding position over the central portion of the tube-like member 4 and is formed of steel or any other suitable material. It comprises a cylindrical side wall I8 and a top wall I9, and has an elongated vertically extending cylindrical expansion chamber 20 therein. This chamber receives a portion of the fuel mixture by way of the tube I 6; as hereinafter described, and is open at its lower end. The lower end of the side Wall IB of the plug I5 is of reduced diameter and fits within a hole 2I in the tube-like member 4. An external screw thread 22 on the lower end of the side wall I8 coacts with an internal screw thread around the outer end of the hole to secure the plug in connected relation with the member 4. The hole 2I extends from the outer periphery of the member 4 ,to the throat I3 of the passage II and constiis located in close proximity to the central portion of the throat. The tube It extends between the plug I5 and the outer or inlet end of the tube-like member 4 and may be formed of any suitable material. One end of the tube extends through and is fixed in a hole 23 in the top wall I9 of the plug I5 and the other end extends into and is fixed Within one branch of an L-shaped duct 24 in the inlet end of the member 4. As shown in Figure 1, the other branch of this duct extends lengthwise of the member 4 and intersects and communicates with the large portion of the mouth I2 of the passagel I. is smaller in diameter than the expansion chamber 20 and serves to conduct a portion of the fuel mixture in the inlet end of the tube-like member 4 to the expansion chamber 20. Due to the fact that the duct 24 communicates with the large end of the mouth I2 of the passage II and the expansion chamber 20 is greater in diameter than the tube I6, the portion of the gas mixture which flows through the tube I6 enters and flows through the chamber 20 at an extremely low velocity and in such a condition or state that it is readily ignitable. The spark plug I1 is of conventional design and consists of a metallic shell 25, an elongated body 26 of insulating material and a pair of electrodes 21 and 28. It is disposed under the central portion of the tube I6 and when supplied with current serves to ignite the fuel mixture in the expansion chamber Ill. The shell 25 surrounds one end of the body 26 and has a reduced externally threaded stem 29 which fits within and extends through an internally threaded hole 30 in the side wall I8 of the plug I5. The electrode 21 extends longitudinally through the body 26 and one end thereof projects through the stem 29 and into the expansion chamber 20 and is spaced from the electrode 28 so as to form a spark gap therebetween. The other or outer end of the electrode 2'I embodies an enlarged externally threaded part for a nut 3| and is adapted to receive current through the medium of a conductor 32 which is clamped by the nut 3| against the contiguous end of the body 26. The electrode 28 is secured to the stem 29 and is grounded through the medium of the plug I5, the tubelike member 4, the ring-shaped plate 8, and the furnace plate f When current is supplied to the electrode 21 by way of the conductor 32 a spark is formed or occurs between the inner end of the electrode 21 and the electrode 2!. This spark serves to ignite the portion of the fuel mixture within the chamber 20 and the flame resulting from combustion of the portion of the fuel mixture within the expansion chamber projects across the throat I3 of the passage II and The tube It causes the fuel mixture passing through the throat to ignite. When the current to the spark plug is cut off combustion of the portion of the fuel mixture in the expansion chamber 20 in the plug l ceases. This is due to the comparatively high suction which occurs in the combustion chamber as the result of the aspirating action of the high velocity stream of fuel mixture passing through the throat and the fact that during normal operation of the burner no combustion takes place within the throat. As a result of the fact that during normal operation of the burner no combustion takes place within the expansion chamber in the plug l5 there is no likelihood of the spark plug l1 becoming fouled with carbon.

When the fuel mixture is supplied under pressure to the tube-like member 4 of the burner the major portion of the mixture flows first into the mouth l2, then at high velocity through the throat l3, and finally at a reduced velocity through the outlet l4 and a less portion of the mixture flows through the tube l6 and passes into the expansion chamber 20, as hereinbefore described. When it is. desired to ignite the burner, current is supplied by way of the conductor 32'to the spark plug l1. As a result of supply of current to the spark plug a spark is formed between the adjacent ends of the electrodes 21 and 28. This spark, as hereinbefore mentioned, ignites the portion of the fuel mixture within the expansion chamber and causes a flame which traverses the throat l3 of the passage II and ignites the main portion of the fuel mixture passing through the throat to the outlet l4. After the burner is started current to the spark plug is cut off. This results in extinguishment of the flame within the expansion chamber 20 of the liig l5 due to the fact that the new of the mixture through the chamber 20 is too high to permit maintained combustion even of very slow burning fuel without continuous igniting by the spark.

The herein described igniting device consists of a small number of parts and hence may be manufactured at, a low and reasonable cost. Due to the fact that the igniting device is located exteriorly with respect to the inlet end of the tubelike member 4, it is notsubject to the heat of the furnace F. In addition the various parts are readily accessible for inspection or repair purposes. Because the'tube l6 for conducting a portion of the fuel mixture under static pressure to the expansion chamber overlies the spark plug I! the plug is protected or guarded from injury.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described theinvention, what I claim as new and desire to secure by Letters Patent is:

1. In combination with a tube-like burner member having one end' thereof adapted for connection to a tuyre in a furnace wall and its other end adapted to receive .gaseous fuel under pressure, and embodying a longitudinal fuel passage. therethrough with an inwardly tapered mouth adjacent to said other end, an igniting device for the burner member comprising means forming an expansion chamber in communication with the passage, means for conducting a portion of the fuel from the mouth to the chamber, and means for igniting the fuel in the chamber.

2; In combination with a tube-like burner member having one end thereof adapted for connection to a tuyere in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying a longitudinal fuel passage therethrough with an inwardly tapered mouth adjacent to said other nd, an igniting device for the burner member comprising means forming an expansion chamber at one side of and in communication with the central portion of the passage, means for conducting a portion of the fuel from the'large portion of the mouth of the passage to the .chamber, and means for producing a spark in the chamber.

3. In combination with a tube-like burner member having one end thereof shaped to fit within a tuyere in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying a longitudinal fuel passage therethrough with .a short inwardly tapered mouth adjacent to said other end, a comparatively long narrow throat of uniform thickness in the central portion of the member and an outwardly flared outlet of intermediate length in said one end of the member, an igniting device for the burner member comprising means forming an expansion chamber at one side of and in communication with the throat of the passage, means for conducting a portion of the fuel from the large portion of the mouth to the chamber, and means for igniting the fuel in the chamber.

4. In combination with a tube-like burner member having one end thereof adapted for connection to a tuyere in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying'a longitudinal fuel passage therethrough with an inwardly tapered mouth adjacent to said other end, and also embodying a transverse hole in the central portion thereof leading to the passage, an igniting device for the burner member comprising a plug fitting within the hole and having an expansion chamber therein in communication with the passage, means for conducting a portion of the fuel from the large portion of the mouth of the passage to the chamber, and a sparking device for igniting the fuel in the chamber, carried by the plug exteriorly with respect to the member.

5. In combination with a tube-like burner member having one end thereof adapted for attachment to the tuyere in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying a longitudinal fuel passage therethrough with an inwardly tapered mouth adjacent to said other end, an igniting device for the burner member comprising means forming an expansion chamber in communication with the passage, a tube on the outside of the member connected to the chamber and the large portion of the mouth of the passage and adapted to conduct a portion of the fuel from said'mouth to the chamber, and means for igniting the fuel in said chamber.

6. In combination with a tube-like burner member having one end thereof adapted for attachment to the tuyere in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying a longitudinal fuel passage therethrough with an inwardly tapered mouth adjacent to said other end, and also embodying a transverse hole in the central portion thereof leading to the passage, an igniting device for the burner member comprising a plug fitting within the hole and having an expansion chamber therein in communication with the passage, a tube on the exterior of the member lead ing from the chamber and communicating with the large portion of the mouth of the passage and adapted to supply fuel from said mouth to the chamber, and means carriedby the plug for igniting the fuel in the chamber.

7. In combination with a tube-like burner member having one end thereof shaped to fit within a tuyre in a furnace wall and its other end adapted to receive gaseous fuel under pressure, and embodying a longitudinal fuel passage therethrough with a short inwardly tapered mouth adjacent to said other end of the memer, a comparatively long narrow throat of uniform thickness throughout in the central portion from the member and having one end thereof connected to the plug and its other end communicating with the large portion of the mouth of the passage, and a spark plug for igniting the fuel in the chamber extending through the plug and positioned between the member and the tube.

DONALD A. CAMPBELL. 

